Concentrating and dehydrating apparatus



Feb. 4, 1941. J. M. HALL y CONCNTRATING AND DEHYDRATING APPARATUS 2sheets-shea 1 Filed April 14, 1958 Feb. 4, 1941. J. M. HALL 2,230,944

CONCENTRATING AND DEHYDRATING APPARATUS Filed April 14, 19582.SheetS-Sheet 2 Patented Feb. 4, 1941 PATENT OFFICE CONCENTRATING ANDDEHYDRATING APPARATUS 4 Claims.

This invention relates to systems for evaporating and -dehydratingliquid products, and the like.

One of the objects of the invention is the provision of a new andimproved dehydrating system employing both air and Vapor or steam as theheating media.

Another object of the invention is the provision of a new and improvedapparatus for evaporating or concentrating a liquid product by the useof mechanism so constructed that the vapor extracted from the product atone stage of its treatment may be utilized for evaporating additionalmoisture from the concentrate at another stage of its treatment.

A further object of the invention is the provision of a new and improvedapparatus for utilizing steam and reusing the uid as a heating mediumfor evaporating a liquid product.

A still further object of the invention is the provision of a new andimproved apparatus for utilizing steam for evaporating a portion of themoisture from a liquid product and desiccating the concentrated productby means of heated air applied to the atomized product in a suitablechamber.

Another object of the invention is the provision of a new and improvedmethod for evaporating and dehydrating a liquid product.

A further object of the invention is the provision of a new and improvedapparatus for concentrating, dehydrating and collecting liquid products,that is simple in construction and that utilizes a minimum of heat inits operation.

Other and further objects and advantages will appear from the followingdescription taken in connection with the accompanying drawings, in

which- I Figs. 1 and 2 are together a side elevation of the apparatus,with `parts broken away and parts in section, and showing the entireapparatus diagrammatically;

Fig. 3 isa section on the line 3-3 of Fig. 1;

Figs. 4 and 5 are sections on the lines I--l and 5 5 of Fig. 2; and

Fig. 6 is a top plan view of the distributor mechanism.

In concentrating and dehydrating liquid food products such as milk andthe like, it is necessary to frequently clean and sterilize theequipment if sanitary conditions are to be maintained. It is a matter ofcommonv knowledge that bacteria thrive under warm temperature conditionsand especially in milk and like products and censequently theseprecautions are necessary in order to prevent unsanitary conditions. Itis evident therefore that any system or apparatus that will reduce thetime and labor necessary for cleaning the equipment is highly desirable.

It is common practice to concentrate the liquid product preparatory todesiccating the same. Heated air is the medium frequently employed forthis purpose, but since air has a low heat capacity, an extended surfaceand air in large volume at high velocity is necessary. On the otherhand, since steam has a high heat capacity Adue to the large amount oflatent heat contained therein, the heating surface may be materiallyreduced thereby effecting a material saving in ,5 time and expense incleaning the equipment.

The present invention employs steam as the heating medium and provisionis made for recirculating this uid so as to conserve the heat. Theapparatus has its boiler or evaporating sur- 20 face greatly reducedover that necessary for the use of gases as a heating medium and thatWithout reducing 4the output of the apparatus.

The apparatus is shown more or less diagrammatically and comprises afurnace l0 having the air heater Il therein, theblower or fan l2 fordirecting air through the heater; the boiler I3 for generating steam asa heating medium; the preheater I4 for preheating the air supplied tothe 3 dehydrator; exhaust blower l5; the main evaporator I and rstliquid collector Il; the auxiliary evaporator I8 and second liquidcollector I9; the condenser 2| exhaust pump 22; liquid reservoir 23;liquid pump 24; dehydrator 25; distributor mechanism 26; separator 21;collector 28; and, receptacle 29 for receiving desiccated material. l

The entire apparatus may be regarded as comprising the furnace mechanismwhich comprises the furnace proper and the mechanism associatedtherewith for imparting heat to the heating media used;the'concentrating mechanism which comprises .the evaporators andattendant liquid collectors and condensing mechanism; the dehydratorwhich also includes the distributor mechanism; and, the separating andcollecting mechanism.

'I'he furnace I0 comprises the bottom wall 3|, the front wall 32, thetop wall 33 and the rear 50 wall 34. A suitable oil or gas burner 35 ismounted in the front wall 32 as shown more clearly in Fig. 1 of thedrawings.l Mounted in the upper portion of the furnace is the air heaterIl which comprises a header 36 secured in the front wall 65 combustionchamber 42.

` ducting steam to the main evaporator I6 which 32 and a header 3'.'secured in the back wall 34. The headers are connected by tubes 38through which air is caused to pass by the fan or blower I2 operated bya motor 39.

The furnace is provided with a baffle wall 4I which extends upwardly -tothe heater I2 and forms with the front wall what may be termed a Thebaille Wall 4I is provided with an opening 43 through which a portion ofthe heated gas in the combustion chamber may pass, the remainder passingupward around the tubes 38 and over the baille w-all 4I for heating theair passing through the tubes. The amount of air directed over thebaille wall may be controlled by reducing the size of the opening 43 byplacing re bricks 44 therein as desired.

The front wall 32 is provided with an opening 45 around which is secureda chamber 46 having a door 41 therefor which may be opened for havingaccess to the interior of the furnace. The chamber 46 is provided withan opening in which is secured one end of a conduit 48 for conductingair from the air collector into the combustion chamber as will presentlyappear.

'Ihe rear wall 34 of the furnace has secured therein one end of a boilerI3 which comprises a chamber 49 through which pass a plurality of fluesor tubes 5I through which the heated gases from the furnace are adaptedto .pass for heating water in the container 49.

The boiler I3 may, if desired, be mounted in 'a casing 52 inthe rear endof which is mounted the preheater I4. The preheater I4 comprises thecasing 52 having the partitions 20 and 38 in which the ends of ues or.tubes 53 are secured. Heated air passing through the boiler I3 from the.furnace passes through the tubes 53 and into .the exhaust fan or:blower I5 which is operated by a motor 54. The exhaust fan I5 exhauststhrough a conduit 55 into the atmosphere. The preheater I4 has anopening 56 on one side at one end thereof which is closed by an air lter51. A conduit 58 is attached at the opposite side adjacent the other endthereof for conducting air to the intake of the blower I2 as shown moreclearly in Fig. 1 of the drawings. The boiler I3 has a steam space 59 inits upper portion and a conduit 6I is in communication with this spacefor conis adapted to contain the liquid product that is beingconcentrated.

The evaporator I6 comprises an upper header 62, a lower header 63, anintermediate casing 40, and tubes 64 extending through said casing andsecured in the .partition walls 5ITand 68 between the headers and`casing for connecting the headers together. Steam from the boilerpasses along the conduit 6I into the casing 40 and aroundl the tubes ofthe main evaporator I6 .for heating the liquid product contained in thetubes 64 and the lower header 63. rhe steam imparts its sensible andlatent heat tothe liquid product which is under .a slight-vacuum, aswill -presently appear, and this steam is thereby condensed and thecondensate, which in .the present instance is water, is returned .to theboiler I3 by a tube or passage 65 by gravity. Fresh -water may be addedto the system through a pipe 10.

In other Words, the boiler I3, conduit 6I, casing 40 and conduit 65 maybe regarded as a closed circuit for one of the heating media. be seenthat after the water has been raised to the boiling point, the steamwill carry thermal units tothe evaporator'where it will give up thoseunits to the liquid product through .the walls of -lector I1 with thepassage 68.

headers together.

It win thus the tubes 64 and will be condensed and the water returnedthrough the .pipe 65 to the boiler to complete the cycle.

The liquid product is contained in the reservoir 23 and is supplied ytothe yheader 63 of the main evaporator by a pipe 19 having a valve 8Itherein for controlling .the flow of the liquid. The header 62 is incommunication with the rst liquid collector I1 through a passage 66which extends into the collector adjacent its upper end. During theoperation of the evaporator I6, a violent ebullition of the liquidproduct will cause steam to carry over particles of liquid in-to thecollector I1 and this liquid will collect in the bottom portion of thiscollector. v

A .passage or tube 68 connects the header 63 with the lower header 12 ofthe auxiliary evaporator I8 and a branch tube 61 connects the col- Thepassage 68 supplies liquid to the header 12 but since the violentboiling of the liquid in the evaporator I6 causes considerably moreliquid to be carried over to the collector I1 than is required for theheader 12, a portion of the liquid in the collector I1 is continuouslybeing returned to the header 63 thus setting up a circulation from thecollector I1 through tubes 61, 68, header 63 and back through passage66. The passage 66 is provided with a baille 69 which directs theparticles of liquid downwardly in .the collector.

The steam passing from the evaporator I6 into the collector is utilizedfor heating the liquid in the auxiliary evaporator I8. This isconsidered an important feature of the invention since it conserves theheat contained in the vapor or steam generated from the liquid .productin the evaporator I6 which in turn was generated by the steam from theboiler, thus conserving the heat originally applied.

The auxiliary evaporator I8 comprises an upper header 1I, a lower header12 and a central or body portion or casing 13 separated from the headers1I and 12 by suitable partitions 14 and 15 in which are secured the endsof tubes 16 which extend through the casing 13 and connect the A conduit11 extends between the upper portion of the collector I1 and the lower`portion of the casing 13 of the auxiliary evaporator.

The steam flowing into the casing 13 through the pipe 11 heats theliquid .contained in the header 12 and tubes 16 and the steam or vapor'from this liquid passes into a second collector I8 where theliquidparticles carried over by the steam lwill be collected in the lowerportion of the second collector. This portion is connected to the header12 through the pipes 82 and 83. The pipes 82 and 83 are connected to themain delivery pipe 84 for conducting the concentrated liquid product tothe dehydrator, as will presently appear.

A conduit 85 conducts the steam from the header 1I into the centralportion of the second collector I9 and a bale 86 directs the liquidparticles carried by it to the bottom of the collector. The upper end ofthe second collector is in communication with a condenser 2 I.

The violent boiling action of the liquid in the evaporator I8 causeslarge quantities of free particles of the liquid in this evaporator tobe carried by the steam over into the collector I9. This thusestablishing a circulation of the liquid from the collector to theevaporator I8 and back again.

'I'he condenser 2| comprises an upper enlarged chamber 81 having arestricted portion 88 in the form of a tube extending downwardlytherefrom. The lower end of the tube extends into an open receptacle 89which is adapted to contain the water of condensation, the level ofwhich is normally above the lower end of the tube 88 for sealing thesame. An overow pipe 9| above the lower end of the tube 88 permits thewater to escape from the receptacle.

The enlarged portion 81 of the condenser 2| contains steam condensingmechanism of any suitable type. As shown, a plurality of ledges 92,arranged in overlapping relation and attached to opposite side walls ofthe condenser, are employed. 'Ihese ledges are in the form of shallowcontainers and the uppermost ledge 92 is supplied with cool water 93 andthis water overflows and falls from one ledge to the other therebycondensing the steam passing over from the co1- lector I9 intothercondenser through the passage 94. 'I'he condensing of this steamcreates a partial vacuum in the condenser since the water in the tube 88constitutes a seal. 'This in turn relieves the pressure in the'collector I9 and auxiliary evaporator. As a result, the liquid productin the auxiliary evaporator is at sub-atmospheric pressure.

In order to prevent the accumulation of air in the condenser and itsinterference with the operation of the apparatus, a vacuum pump 22 isemployed for removing such air.

The lower end of the casing 13 of the auxiliary evaporator is connectedto the condenser at the lower end of the enlarged portion 81 by a pipeor tube 95. As the heat in the vapor that passes into the casing 13 isabsorbed by the liquid product contained in the tubes 16, the vaporcondenses tending to create a partial vacuum whereby the pressure in theevaporator I6, header 62 and casing I3 are sub-atmospheric. The water ofcondensation is discharged from the casing 13 through the tube 95attached to the lower portion of the casing 13 and to the enlargedportion of the condenser 81. The column of water in the tube 95constitutes a seal and the height of the column determines the pressurein the casing 13, collector I1 and header 62 of the main evaporator I6.The pressure in both collectors is subatmospheric due to the condensingof steam in the condenser 61 and in the casing 13 and since the header1| may be said to be in direct communication with the condenser 81 whilea column of water in the tube 95 may be said to be interposed betweenthe header 62 and the condenser-81, it follows that the pressure in theheader 62 is greater than in the header 1| due to the additionalpressure required to overcome the Weight of this column of water.

It has been found that the device operates satisfactorily if the vacuumin the header 62 is around twenty inches and that in the header 1| isaround twenty-six inches.

In the operation of the device, liquid product from the container 23 isadmitted to the main evaporator and is contained in the header 63 andthe tubes 64. `Steam from the Boiler I3 is delivered to the casing 48between the headers and among the tubes for heating the liquid containedin the tubes'and the vapor from this ,liquid together with liquidparticles passes over into the iirst collector where the liquid isdeposited in the bottom of the collector and the steam from the liquidyproduct passes over intol the auxiliary evaporator through the passage11. The steam passing through the conduit 11 is delivered to the casing13 of the auxiliary evaporator from the header 62 of themain-evaporator. The steam or vapor generated from the liquid product inthe auxiliary evaporator, together with particles of the liquid, passesvinto the second collector where the liquid content drops to the bottomand the vapor passes over into the condenser 2| where it is condensed.The vapor passing over from the collector I1 to the casing 13 of theauxiliary evaporator is condensed in the auxiliary evaporator and thecondensed liquid is forced through the pipe 95 by the pressure in thecollector I1. 'I'he height of this pipe determines the pressure of thevapor in the rst separator and main evaporator as pointed out above.

It-will thus be seen that the liquid, or a por- Y tion of it, passingover into the collector I1 may flow back into the header 63 by gravitythereby forming a circuit from the evaporator to the collector and backagain for evaporating still further moisture from the liquid product.Likewise, the liquid, of course, is free to flow along the pipe 68 intothe header 12 which it does when the pressure in the header 12 islowered as when liquid is removed for dehydrating. Likewise, the liquidcollected in the second collector I9 may be returned to the header 12 tobe further evaporated thus establishing another system of circulation.The condensed liquid product passes from the tubes 82, 83 into the mainsupply pipe 84 where it passes throughlthe pump 24 which delivers it tothe distributor 26 of the dehydrator 25.

This distributor comprises an atomizer head 91 having a hollow spindle98. The atomizer head 91 is adapted to be rotated at a high speed by asuitable motor 98. The head 91 atomizes the -condensed liquid productand discharges the same in umbrella form in the interior of thedehydrator as is usual in such constructions.

Suitable means are provided for directing heated air downwardly over theatomizing head 91 and across the periphery of this head. As shown, theair heater I has a conduit I 8| for conducting the air from the heaterto a circular passage or snail |82 surrounding the spindle 98 on the topof the ,dehydraton The circular passage or snail |82 causes the airwhich enters the passage tangentially, Fig. 6, to rotate at highvelocity as it is deliveredthrough the pipe |8I. Air is supplied to theheater by the fan or blower I2, the intake vof which is in communicationwith the passage 58 which conducts air from the preheater |11.

Air from vthe circular passage or snail passes downwardly through asleeve |83 into the dehydrator 25. This sleeve extends about the spindle98 which is protected by a sleeve of insulating material |85 against theheat of the air passing downwardly through the cylinder |83 which wouldotherwise injuriously affect the liquid product such las milk flowingthrough the hollow spindle.

A conical shield |86 is mounted above the rotating head 91 for directingthe heated air outwardly over the edge of said head and'for protectingsaid head. The head 91 may be rotated in a direction counter to that ofthe Lair passing downwardly through the cylinder |83` or it may berotated in the same direction as said air. Since the details of theatomizer constitute no part of the present invention, the same is shownmore or less diagrammatically and a detailed description is deemedunnecessary.

Suitable means are provided for collecting the dehydrated material inthe vbottom of the dehydrator 25. As shown, the lower end Wall of thedehydrator is sloped inwardly as shown at |01 and its inner edge isconnected to the upper edge of a trough or channel |08 extending aroundthe lower end of the dehydrator. The upper edge of the inner wall of thechannel or trough |08 is connected to the Wall of a cone |09 whichextends upwardly within the dehydrator 25 axially and is so arrangedthat material falling on the inclined wall of the cone will be conductedinto the trough |08. The Wall of the cone |09 extends into the channelor trough |08 so as to form a restricted opening in the upper portion ofsaid trough so that the material is free to slide into the trough butthe overhanging edge of the wall of the cone and the side wall |01 willtend to prevent the air delivered in the trough from flowing upwardly7into the separator. 'The channel |08 increases in size from its entranceto its delivery end as shown more clearly in Fig. 3 of the drawings.

The air delivered by the conduit |-0I and carrying the dehydratedmaterial with it is exhausted through the passage |08 and conduit |23into the air separator 21. The air delivered by the conduit |0| is dry,warm air usually in the neighborhood of 500 degrees but in evaporatingthe moisture contained in the atomized particles of the liquid product,the air becomes more or less saturated and for that reason thedehydrated particles have a tendency to stick to the walls of thechannel or trough |08. It has been found that if the velocity of the airin the channel |08 is increased, especially if its temperature beslightly lowered, the material will not collect on the walls of thetrough during the operation of the device.

Suitable means are provided for increasing the speed of this air andalso for cooling the same. In the form of the device shown, a conduit |2is provided for this purpose. One end of this conduit is incommunication with the small end ||3 of the channel |08 and the otherend is connected to the pipe ||4 leading from the collector 28 to thechamber 46 of the furnace A valve ||5 is provided for controlling theamount of air delivered through the conduit |2.

Suitable means are provided for introducing cool air into the pipe ||2and channel |08. As shown, a branch conduit ||B is connected to theconduit ||2 and has its other end connected to the discharge side of afan or blower 1 which is operated by a motor ||8. The intake ||9 of thefan is provided with an air filter |2| for filtering the air admitted tothe system. A valve |22 is provided for controlling the amount of airadmitted to the pipe ||2 from the fan ||1. The enlarged end of thetrough or channel |08 is connected to a discharge conduit |23, Figs.l'and 3, which conducts the air and dehydrated material to the separator21. The separator 21 is operated by a suitable motor |24 and is of theusual or any well known construction. Since the details of the separator21 constitute no part of the present invention, the separator is shownmore or less diagrammatically yThe material separated from the airpasses into the reservoir 29 which is connected with an airtightconnection to the discharge side of the separator and from the separatorthe material may be discharged through a suitable rotary valve |25operated by a motor |26. The air discharged from the separator 21 willcontain more or less of the dehydrated material and for this reason theair con-taining the material may be passed through .a collector 28. Apipe |21 connects the discharge side of the separator 21 tothe intakeside of the collector 28. The material collected may be discharged fromthe collector through a rotary valve |28 as is usual in suchconstructions.

The air, freed from the dehydrated material, is discharged from thecollector into Ithe conduit I4 which delivers the air .to the furnacefor aiding in combustion as has been previously described.

In the operation of the dehydrator, the liquid product is supplied tothe head 91 which atomizes the same and the hot air from the furnace issupplied through the conduit |0| for dehydrating the material in thedehydrator 25. The dehydrated material falls to the bottom of thedehydrator and passes with the air into the channel or trough |08 Whichconducts the same to the evaporator and collector where it is separatedfrom the air and the air delivered to the furnace.

It is thought from the foregoing that the construction and operation ofmy device will be apparent to those skilled in the art and that changesin size, shape, and proportion may be made without departing from thespirit and scope of the appended claims.

I claim as my invention:

l. In a dehydrating apparatus, a furnace for generating heated gases, acombined boiler and air preheater, an air heater, means for passing saidheated gases in series through said air heater, boiler and preheater inthe order named, an evaporator for containing a liquid product to beevaporated, a conduit forming 'a closed circuit With said evaporator andboiler for circulating steam generated in said boiler through saidevaporator, a dehydrator, means for conductingv the concentrate fromsaid evaporator to said dehydrator, means in said dehydrator foratomizing said concentrate, and means for causing air to iow throughsaid preheater and air heater into said dehydrator for dehydrating theatomized material, and means for returning a portion of said air to saidfurnace for assisting in combustion.

2. In a system for dehydrating liquid products,

a primary evaporator for containing a liquid product, a secondaryevaporator for receiving the concentrate fromsaid first-namedevaporator, means for evaporating moisture from the liquid in saidprimary evaporator, said means comprising a boiler for heating a fluidand conduits for vconducting said fluid to said primary evaporator andback to said boiler for heating said evaporator, means for utilizing thesteam generated in said primary evaporator for evaporating moisture fromthe concentrate in said secondary evaporator, a furnace, an air heater,a preheater, means for causing heated gases from said furnace to iiowthrough said air heater, said boiler and preheater in the order named, adehydrator, means for spraying said product in said dehydrator, meansfor conducting fresh air through said preheater and air heater into saiddehydrator for dehydrating said product sprayed therein, and a conduitfor discharging the gases passing through said furnace, air heater,boiler and preheater into the atmosphere.

3. In a system for desiccating a liquid product, an evaporator, adehydrator, a liquid product reservoir, means for conducting saidproduct to said evaporator for condensing the same, means for conductingthe concentrate from said evaporator and for spraying the same into saiddehydrator, a furnace, an air heater, a boiler, a preheater adjacent tosaid boiler, means for causing heated gases from said furnace to flowthrough said air heater, then through said boiler and nally through saidpreheater for heating the air heater, boiler and preheater, means forrecirculating a fluid through said boiler and evaporator, and means forconducting fresh air first through said preheater, then said air heaterand finally delivering the same into said dehydrator for desiccatingsaid product.

4. In a system for dehydrating a liquid product, an air heater, afurnace, a preheater, a boiler, means for causing combustion gases fromsaid furnace togpass through said air heater, Loiler and preheater insaid order and for discharging the same from said system, an evaporator,means for conducting an aqueous uid from said boiler to said evaporatorin a closed circuit for concentrating said product, a dehydratorchamber, means for discharging the concentrated product into saiddehydrator chamber in finely divided particles, means including a fanfor causing air to flow through said preheater, through said heater andinto contact with said particles for dehydrating the same, a circularchannel in the lower portion of said dehydrator chamber for receivingthe dehydrated particles of said product, an air separator, means forconducting the mixture of the dried particles and said air to saidseparator for separating the dried particles from the air, means fordirecting a blast of fresh air into said channel for increasing thevelocity of the mixture of air and particles and for cooling saidparticles, and means for conducting a portion of the air from saidseparator to said channel and the remainder to said furnace.

JOSEPH M. HALL.

